Expansion valve



y 1931. F. E. osflmsoN ETAL 1,307,200

EXPANSION VALVE Original Filed Jan. 29, 1926 Ma! @jjfelamd Patented May26 1931 FRENCH E. DENNISON AND WARD S. IRELAND, OF IBELOIT,

WISCONSIN, ASSIGNORS TO NATIONAL REFRIGERATION CORPORATION, OF BELOI'I,WISCONSIN, A CORPORA- TION OF DELAWARE EXPANSION VALVE Originalapplication filed January 29, 1926, Serial No. 84,573. Divided and thisapplication filed June 18,

1928. Serial This invention has been divided pursuant to a requirementof division from copending application Serial No. 84,573,v filed January29, 1926, and relates in general to valves and has more particularreference to expansion valves adapted for use in mechanicalrefrigerating apparatus.

Prior to our invention considerable dificulty has been encountered inthe operation of expansion valves first from the fact that it has beenpractically impossible to prevent leakage past the valve, particularlyafter the valve has been in use for some time. This leakage has resultedeither from the fact that the valve did not originally accurately'fitits seat or from a slight displacement of the valve relatively to itsseat while in use, or from minute particles of dirt, grit, sediment orsome foreign substance which would become lodged between the valve andits seat so as to prevent accurate and complete seating of the valve, orfrom the abrasive action of foreign particles against the seat and valveor from wire drawing. In some installations, a slight leakage is not ofextreme importance, but in installation requiring low temperature to beheld within close minimum and maximum ranges, even a minute leakagematerially diminishes the efliciency of the machine. Another cause ofdissatisfaction with existing expansion valves resides in the fact thatconsiderable friction is involved in their operation so that they arenot as delicate as they should be and since this friction usuallyincreases with the age of the valves they operate poorly and sometimeseven become stuck in closed or more often opened or partially openedposition.

One of the primary purposes of our present invention. is to provide anexpansion valve which will eliminate the wear from abrasive action offoreign particles, will not be subject to the wire drawing and will behighly eflicient and wholly accurate in operation so that it may beopened and closed an infinite number of times without sticking and willfully and completely close so as to entirely preclude any leakage.

With this general purpose in view, our invention' contemplatesimprovements in many of the structural features of an expansion valveincluding the seat, the valve itself, the mounting of the valve, theguides and other devices which control and actuate the valve.

The improvements and novel features of construction involved in thevarious elements above mentioned as well as others will be more fullyappreciated as the invention becomes better understood by reference tothe following description when considered in connection with theaccompanying drawings.

Referring to the drawings:

Fig. 1 is a vertical sectional view through an expansion valve embodyingour invention,

Fig. 2 is a fragmentary sectional View on the line 2-2 of Fig. 1, and

Fig. 3 is. a detailed perspective view of the valve lifting or unseatingdevice.

Referring to the drawings more in detail,

.the valve casing comprises generally the body 5 provided with the inletpassage 6 adapted to be connected to the liquid supply line, the outletpassage 7 adapted to be connected to. the expansion coils, the cap orbonnet 8 secured to the body by bolts 9, and the bottom 11 secured tothe body by bolts 12.

An annular chamber 13 is formed in the body and within this .chamber isdisposed a cylindrical member 14-. provided at its upper end with acentral bore 15 and at its lower end with a central bore 16. These boresare separated by a partial wall 17 provided with a central passage 18and shaped to accomodate a valve seat 19, the structure and function ofwhich will be later described more" fully. Radially disposed ports-21establish .communication between the chamber 13 and 1 the upper centralbore 15, through a filter to be later described.

The valve seat 19 is formed of a suitable alloy possessing suflicientrigidity so that it will not flow or become distorted under the normalpressure of the valve against the seat but at the same time beingsufficiently soft so that it will conform to the valve itself when thevalve, which is of hard'metal, or a similarly shaped hardened hob, isforced against the seat under very high .pressure. It will be observedthat the valve proper 22 has a tapered seating portion and when thisportion or a similarly shaped portion of a hob is forced under highpressure against the seat, the seat will be pressed to shape so as tosnugly and tightly fit the valve thus providing a better and moresatisfactory fit than could be produced by grinding the seat or lappingthe seat and valve together and not only is a tighter and moreleak-proof fit assured but the expense of production as compared withgrinding or lapping both the valve and seat which are customary, is verylow.

The seat, in addition to its characteristic of rigidity againstdeformation under ordinary working pressure of the valve and itscapability of conforming to the shape of the valve under high pressure,is sufliciently soft so that particles of grit, dirt, sediment or thelike which may become deposited on the seat notwithstanding the finemesh filter which will be later explained, will not hold the valve awayfrom its seat and thereby permit leakage but will under the pressure ofthe valve become imbedded in the surrounding seat itself so thatnotwithstanding the presence of these foreign particles, the valve willclose fully and snugly against its seat.

The seat is fitted and secured so snugly-in the recess in the partitionwall 17 that any leakage around the seat is precluded.

While the seat is preferably formed of an alloy possessing thecharacteristics above mentioned, an alloy of approximately 27 parts tinand one part silver, such as disclosed in Patent No. 1,626,038, beingadmirably suitable for the purpose, and the valve proper 22 ispreferably of extremely hard material such as tungsten, a reversal, thatis a hard seat and a soft valve is contemplated within the purview ofour invention.

In order to obviate any danger of the valve getting off-centerwithrespect to the seat, and for the purpose of insuring that the valvewill always be self-centering, the valve is loosely mounted in its guideso that it may, in effect, be said to float. With this end in view, theguide 23 is provided with a valve receiving bore 24, slightly larger indiameter than the valve proper 22, thus affording a loose fit, and theupper end of the valve proper has substantially a point contactdiaphragm to flex upwardly,

the push pin 29 to open the valve and an inagainst a hardened ball 25 orother curved member. The very small contact area between the ball andthe valve facilitates the lateral movements of the valve, thus enablingit to automatically center itself and accurately contact with its seat.

.The valve is normally urged toward its seat by an expansion spring 26interposed between the outer end of a cap 27 threaded onto thecylindrical member 14 and an equalizing member 28 resting upon the topof the guide 23. For the purpose of obviating friction which wouldresult from any lateral or diagonal pressure applied to the guide 23,the member 27 has a tapered bottom to provide substantially a pointcontact with the guide 23, thereby enabling the equalizing member 28 totilt and accommodate itself to the position and shape of the spring andimpart only a direct downward thrust to the guide which has no tendencyto cause it to bind against the side walls of the bore 15 and therebycause a jumpy or irregular openin and closing of the valve. With theview 0% further reducing to. a minimum the friction between the guide 23and the surrounding walls of the bore 15, the guide is made polygonal incross section as will be apparent from an inspec tion of Fig. 2, so thatit has substantially line contacts with the walls of the bore instead ofsurface contact of considerable area, as would be the case if both thebore and the guide were circular in cross section.

The valve is lifted off from its seat against the force of the spring 26so as to permit a flow of fluid through the device, by means of a pushrod or pin 29 projecting upwardly into engagement with the lower end ofthe valve 22. This push pin is formed on the upper end of a body 31which is adjustably threaded upon an upstanding stud 32 and locked inadjusted position by a lock nut 33. The body 31 is also polygonal inshape as will be apparent from Fig. 3 to reduce the friction between itsperimeter and the surrounding walls of the bore 16 within which it isdisposed. The stud 32 is provided at its lower end with a flat disc-likehead 34 which rests loosely upon the upper face of a diaphragm 35clamped at its margins between the opposed faces of the body 5 and thebottom- 11. The chamber 36 above the diaphragm is in constantcommunication with the outlet passage 7 of the valve and is there foresubjected to variations in pressure in the low pressure side of therefrigerating system. A decrease in pressure below normal in the chamber36 and consequently upon the upper face of the diaphragm 35 will permitthe thereby lifting crease 1n pressure in this chamber will depress thediaphragm, permitting the valve to be closed against its seat under theinfluence of the spring 26 The valve is balanced and adjusted so as toclose under the requisite predetermined pres sure by means of anadjusting screw 37, threaded through the wall of the bottom 11 andcarrying a head 38 between which and a cap 39 is interposed an expansionspring 41. It will be obvious that the spring 41, being opposed to thespring 26, adjustment of the spring 41 will serve to regulate theopening and closing movements of the valve with a fine degree of nicetyto any pressures which it may be desirable to maintain in the low sideof the system.

In the annular chamber 13, through which all fluid must pass from theinlet passage 6 to the valve proper through the radial ports 21, we havemounted a filter screen, which is clearly shown in Figs. 1 and 2. Thisscreen is cylindricalin shape and comprises a lura-lity, in the presentinstance, three cylindrical screens designated respectively by referencecharacters 42, 43, and 44. These screens are made of fine mesh wirecloth. The meshes are preferably of progressively increasing fineness,that is, screen 42 is the coarsest and screen 44 the finest. The upperand lower margins of these screens are imbedded in and sealed by upperand lower metallic rings 45 and 46. The structure of the filter itselfand the method of making the same forms thesubject matter of a copendingapplication, Serial No. 84,574, filed January 29, 1926. The filter issnugly clamped between the lower end of the cap 27 and an annularshoulder formed on the perimeter of the central member 14. A gasket 48prevents leakage from the casing above the screen. Leakage around thescreen at the bottom is precluded by a gasket 49 interposed betweenopposed shoulders on the center member 14 and the body 5, the gasketbeing compressed between these shoulders by a nut 51 threaded onto thelower end of the member 14 as shown in Fig. 1.

It will be apparent therefore that the valve proper is sealed againstthe entrance thereto of any fluid or solid whatsoever, except such-asmay pass through the filter, and this filter is so designed andconstructed that only the minutest particles of solid matter of suchsmall size that they are practically invisible to the naked eye canpass. Should these extremely small particles become lodged upon the seatof the valve, the structure of the seat is such that if the particle isnot crushed between the opening faces of the seat and the valve properwhen the valve is forced against the seat it will be forced into andimbedded in the seat itself, which is, as previously explained,sufiiciently soft to permit minutest particles which are too hard to becrushed to be forced into the metal of the seat, so that the valve inevery instance will snugly engage its seat with a leak-tight fit. Itshould also be manifest that thevalve is so constructed that frictionbetween the moving parts is reduced to a minimum, and any danger offaulty operation as the result of friction is obviated.

The operation of our invention should be apparent without furtherdescription, and While we have shown and described a preferredembodiment of the invention, the structural details which we have shownand described may be varied without departing from the essence of theinvention nor from the scope of the following claims.

We claim:

1. In a valve, the combination of a casing provided with a valve seat, acircular bore extending upwardly from said'seat, a polygonal valve uideslidably disposed in said bore and provi ed at its lower end with asocket, a ball disposed in said socket, and a valve projecting into saidsocket and engaging said ball, said guide through said ball beingadapted to force said valve against its seat.

2. In a valve, the combination of a casing provided with a valve seat, acircular bore extending from said seat, a valve guide slidably disposedin said bore, a valve proper loosely fitted in said guide for limitedlateral movement therein, a thrust ball interposed between the guide andthe valve, a spring for exerting pressure upon the valve through theguide, and a pivotally mounted equalizing member interposed between saidspring and said guide.

3. In a valve, the combination of a body, a center member projectinupwardly in said body, a valve seat carried y said center member, aguide slidably disposed in said center member above the seat, a valveconnected with said seat, a loose connection including a ball in saidguide, a cap threaded onto the end of said center member,'an equalizingmember pivotally disposed upon the upper end ofsaid guide, and anexpansion spring interposed between said equalizing member and the upperend of said cap.

4. In a valve, the combination of a seat, a valve guide, a valve looselyfitted in said guide for reciprocal movements and for limited transversebodily movements therein, and a thrust member having substantially apoint thrust contact with said valve so as to permit the valve to movetransversely and center itself when urged against said seat by saidmember.

5. In a valve, the combination of a valve body provided with a centerbore, a valve seat at one end of said bore, a valve guide reciprocablein the other end of said how, a valve proper loosely fitted in saidguide forlimited a valve guide with-a valve loosely mounted in saidguide for reciprocal movements and for limited transverse bodilymovements, and a thrust ball in contact with a plane surface of saidvalve, means for exerting a pressure upon said ball whereby pressure istransmitted through said ball to said valve towards its seat and meansfor exerting a pressure upon the other end of said valve to urge it awayfrom said seat and into said guide.

In witness of the foregoing We affix our signatures.

FRENGH E. DENNISON. WARD S. IRELAND.

